Brand Premarin

Common use

Premarin is a mixture of estrogen hormones which regulates development and functions of female reproductive system, formation of female secondary sex characteristics. On entering into the bloodstream it forms a complex with a specific receptor (in the fallopian tubes, cervix, excretory ducts of the mammary glands, vagina, urethra, breast, liver, hypothalamus, hypophisis), stimulates synthesis of DNA and proteins. It results in proliferation of the epithelium, increased sensitivity of the uterus and tubes muscles of to medications stimulatign their motility. This medication decreases bone resorption of Ca2 + in menopause, prevents involution of the genitals. Premarin is used to treat symptoms of menopause which include hot flashes, vaginal dryness, vaginal irritation and dryness, to prevent osteoporosis in postmenopausal women. Replacement therapy in peri- and postmenopausal women, ovarian hypofunction (primary and secondary amenorrhea, oligomenorrhea, dysmenorrhea) and other conditions.



Dosage and direction

Take this medication once daily as prescribed with a full glass of water with or without food. Premarin may be administered for a cyclic treatment which consists of 25 days on followed by 5 days. Do not take in larger amounts than prescribed. Individual dosage depends on your condition (for hypogonadism 0.3 mg or 0.625 mg daily, for preventing postmenopausal osteoporosis is 0.3 mg/day). Try your best to take it regularly to get the best benefit from it. Do not take with grapefruit juice, it increases levels of estrogen.



Precautions

Long-term treatment with Premarin may increase risk of breast cancer, endometrial hyperplasia, heart attack, or stroke so monitoring of the patient's state should be done on a regular basis. This medication can be harmful to an unborn baby, do not use it during pregnancy. Do not use Premarin to prevent hart disease or dementia. To avoid endometrial hyperplasia you may be prescribed to take a progestin together with Premarin. Do not use this drug if you are under 18 y.o..



Contraindication

Hypersensitivity, pregnancy, breastfeeding, estrogen depending malignant tumors, undiagnosed genital or uterine bleeding, thrombophlebitis or thromboembolic disease in active phase (excluding treatment of breast and prostate cancers). Cautiousness should be exercised in patients with thrombophlebitis, thrombosis or thromboembolism (while taking estrogens in history); family hyperlipoproteinemia, pancreatitis, endometriosis, gallbladder disease in history (especially cholelithiasis), severe liver failure, jaundice (including one during pregnancy in history), hepatic porphyria, leiomyoma, hypercalcemia associated with bone metastases caused by breast cancer, underactive thyroid, porphyria, endometriosis, asthma.



Possible side effect

You may experience symptoms of allergy (hives, rash, swelling face and tongue) and also chest pain or heavy feeling, sudden numbness or weakness, abnormal vaginal bleeding, migraine headache, confusion, jaundice, swelling in hands, ankles, or feet. If such symptoms are severe stop taking this medication and notify your doctor at once.



Drug interaction

Estrogens stimulate the liver's ability to produce factors that promote the clotting of blood. Thus, concomitant administration of Premarin and warfarin (blood thinner) may cause decrease their effects. Barbiturates, Rifampin (Rifadin), phenytoin (Dilantin), carbamazepine (Tegretol), griseofulvin (Grifulvin), St. John's wort and primidone increase metabolism of estrogens. Erythromycin, ketoconazole (Nizoral), itraconazole (Sporanox), and ritonavir (Norvir) act oppositely.



Missed dose

Take the missed dose as soon as you remember about it. If it is almost time of your next dose just skip it and return to your regular schedule.



Overdose

Immediate medical attention in needed in case you overdosed intake of the medicine. Symptoms may include vomiting, nausea, and vaginal bleeding.



Storage

Premarin should be stored at room temperature, between 15-30 C (59-86 F). The right temperature to store the injection is between 2-8 C (36-46 F).



Disclaimer

We provide only general information about medications which does not cover all directions, possible drug integrations, or precautions. Information at the site cannot be used for self-treatment and self-diagnosis. Any specific instructions for a particular patient should be agreed with your health care adviser or doctor in charge of the case. We disclaim reliability of this information and mistakes it could contain. We are not responsible for any direct, indirect, special or other indirect damage as a result of any use of the information on this site and also for consequences of self-treatment.

Clinical Verification

Last Clinically Updated: August 15, 2026

Written By

Dr. Elena Vance, PharmD

Clinical Specialist in Neuropharmacology

Fact Checked By

Marcus Thorne, MS

Biomedical Data & FDA Label Verification

Medically Reviewed By

Dr. Arthur Campbell, MD

Board-Certified Psychiatrist (ABPN)